Arthur Hodgkiss - a master gem thief - is in London, about to realise his lifelong ambition to steal the Crown Jewels. But he is mistaken for Chinese agent, Kung Fu Tzu, and is unwittingly given a package containing stolen top secret government plans.

Enter British Intelligence who put their top man on the job: the suave, fearless ladies' man, Jerry Cornell. There ensues a chaotic comedy of errors in which Jerry Cornell pursues Kung Fu Tzu, the titular Chinese agent, who is in turn pursuing Arthur Hodgkiss, who was given the secret plans for which Cornell is pursuing Kung Fu Tzu.

In this perfect circle of bluff and counter-bluff, the only one thing that is certain is that nothing can be known for sure.